US swimmer Diana Nyad, 64, greets her support team before her swim to Florida from Havana, Cuba, Aug. 31, 2013. Ramon Espinosa/AP

US swimmer Diana Nyad, 64, jumps into the water off Havana, Saturday, to set an open-water record by swimming from Cuba to the Florida Keys without a protective shark cage, Aug. 31, 2013. Ramon Espinosa/AP

Diana Nyad, positioned about two miles off Key West, Fla., Monday, is escorted by kayakers as she swims towards the completion of her approximately 110-mile trek from Cuba to the Florida Keys. Nyad, 64, is the first swimmer to cross the Florida Straits without the help of a shark cage. Florida Keys News Bureau/Andy Newman/AP

US endurance swimmer Diana Nyad poses before a press conference announcing her 2011 attempt to swim from Cuba to Key West, Fla., Aug. 7, 2011. Ms. Nyad began her journey on Aug. 7 but had to cancel the attempt 29 hours later. Franklin Reyes/AP

Diana Nyad plays a trumpet before her 2011 attempt to swim to Florida from Havana. Ms. Nyad was inducted into the National Women's Hall of Fame in 1986 and the International Swimming Hall of Fame in 2003. Appropriately, 'Nyad' is a variant of the Greek name Naiad, which means 'water nymph.' Desmond Boylan/Reuters

Diana Nyad meets with reporters before her attempt to swim to Florida from Havana on Aug. 7, 2011. The same swim was completed by Australian Susan Maroney in a shark cage in May 1997, but Ms. Nyad swam without the cage, protected by a surrounding electrical field and by divers watching for sharks. Desmond Boylan/Reuters

Diana Nyad speaks to reporters before jumping into Cuban waters in Havana on Aug. 7, 2011. In 1979, Nyad swam from Bimini to Florida in two days, setting an unbroken distance record for nonstop swimming without a wetsuit. She has broken numerous world records, including circling Manhattan Island in 1975 in 7 hours and 57 minutes. She first attempted the Cuba-Florida swim in 1978. Franklin Reyes/AP

Diana Nyad looks at the ocean before beginning her 2011 attempt to swim to Florida from Havana. Enrique De La Osa/Reuters

Diana Nyad jumps into the sea as she begins her attempt to swim to Florida from Havana on Aug. 7, 2011. Desmond Boylan/Reuters

Followed by Stuart Nex, a member of her team, Diana Nyad swims in Cuban waters, Aug. 7, 2011. Franklin Reyes/AP

Diana Nyad swims between Cuba and Florida while accompanied by two assistants in kayaks and an assistance boat on Aug. 7. Instead of swimming in a shark cage, which provides a helpful draft for the swimmer, Nyad will be protected by an electrical field and by divers who will watch for sharks and drive them away if they get too close. Desmond Boylan/Reuters

Diana Nyad swims toward Florida from Havana, Aug. 7, 2011. She had to abort the swim about 29 hours later. In 1978, during her first attempt, Nyad quit after swimming almost 42 hours because of strong currents and rough weather that banged her around in the shark cage she was using then. Desmond Boylan/Reuters

Diana Nyad has made it farther than in any of her previous four tries. If she succeeds, Nyad will be the first person to swim the 112-mile distance without a shark cage.

ByJennifer Kay, Associated PressSeptember 2, 2013

Ramon Espinosa/AP

With her lips and tongue swollen, US endurance swimmer Diana Nyad edged closer to Florida on Monday in her attempt to become the first person to swim the treacherous waters from Cuba to Key West without a shark cage.